Electrospun nanofiber-reinforced three-dimensional chitosan matrices: Architectural, mechanical and biological...

The poor intrinsic mechanical properties of chitosan hydrogels have greatly hindered their practical applications. Inspired by nature, we proposed a strategy to enhance the mechanical properties of chitosan hydrogels by construction of a nanofibrous and cellular architecture in the hydrogel without toxic chemical crosslinking. To this end, electrospun nanofibers including cellulose acetate, polyacrylonitrile, and SiO₂ nanofibers were introduced into chitosan hydrogels by homogenous dispersion and lyophilization. With the addition of 30% cellulose acetate nanofibers, the cellular structure could be maintained even in water without crosslinking, and integration of 60% of the nanofibers could guarantee the free-standing structure of the chitosan hydrogel with a low solid content of 1%. Moreover, the SiO₂ nanofiber-reinforced chitosan (SiO₂ NF/CS) three-dimensional (3D) matrices exhibit complete shape recovery from 80% compressive strain and excellent injectability. The cellular architecture and nanofibrous structure in the SiO₂ NF/CS matrices are beneficial for human mesenchymal stem cell adhesion and stretching. Furthermore, the SiO₂ NF/CS matrices can also act as powerful vehicles for drug delivery. As an example, bone morphogenetic protein 2 could be immobilized on SiO₂ NF/CS matrices to induce osteogenic differentiation. Together, the electrospun nanofiber-reinforced 3D chitosan matrices exhibited improved mechanical properties and enhanced biofunctionality, showing great potential in tissue engineering.